1. To detect and measure, in vitro, the non-covalent binding of prostaglandins E (PGE1 and PGE2) and prostaglandin F2 alpha (PGF 2 alpha) to human serum albumin, human serum proteins, and human uterine components, respectively; 2. To determine the binding parameters of the prostaglandin macromolecule interactions and study the physical characteristics of the PG- binding components. Human uterus can produce prostaglandins and is a likely target organ of prostaglandins. The propsoed study could contribute to a better understanding of the mechanism of action of prostaglandins at the molecular level, while the use of human material bypasses the difficulties inextrapolating from animal studies.